diff --git a/include/cantera/base/ctml.h b/include/cantera/base/ctml.h
index 347f3a99a..f82b46e1c 100644
--- a/include/cantera/base/ctml.h
+++ b/include/cantera/base/ctml.h
@@ -588,6 +588,7 @@ bool getOptionalFloat(const Cantera::XML_Node& parent, const std::string& name,
  * @param node     Current XML node to get the values from
  * @param v        Output map of the results.
  * @param convert  Turn on conversion to SI units
+ * @param deprecated Unused. To be removed in Cantera 2.2.
  */
 void getFloats(const Cantera::XML_Node& node, std::map<std::string, double>& v,
                const bool convert=true);
diff --git a/src/base/ctml.cpp b/src/base/ctml.cpp
index 7caf5e1e1..00940ce4c 100644
--- a/src/base/ctml.cpp
+++ b/src/base/ctml.cpp
@@ -228,6 +228,8 @@ void getIntegers(const Cantera::XML_Node& node,
 void getFloats(const Cantera::XML_Node& node, std::map<std::string, double>& v,
                const bool convert)
 {
+    warn_deprecated("ctml::getFloats",
+                    "To be removed in Cantera 2.2.");
     std::vector<XML_Node*> f;
     node.getChildren("float",f);
     int n = static_cast<int>(f.size());